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Direct mode vs stereo mode

Discussion in 'AV Receivers' started by RobWil, Apr 8, 2003.

  1. RobWil

    RobWil Well-Known Member

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    Kind of related to another thread in the Subs and Speakers forum, and something I was thinking about last night.
    Listening to some smooth jazz type music like Spyro Gyra, Peter White, Jazzmasters last night I was switching back and forth between direct and stereo modes.
    This really sucks cause the direct mode sounds best for mids to highs and for soundstage and imaging, but in stereo mode the bass sounds so much better because of the decent subwoofer. And I'm thinking 'Damn', which one do I want? So I end up switching back and forth, enjoying the nice tight, musical bass, and then the beautiful detail and imaging, back and forth, back and forth...trying to decide, and I can't. So what is the answer? To run the fronts through the sub and use the sub crossover? Or by running through the sub are you defeating the advantage of going pure direct? Or is there something I don't know about that would enable me to have both?
     
  2. Chriss M

    Chriss M Well-Known Member

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    an outlaw ICBM, or similar high quality analog crossover would allow you to have both.
     
  3. RobWil

    RobWil Well-Known Member

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    Hey..thanks, Chriss. Could you elaborate a little on how this works? Or would I just be correct in assuming that it's the lower quality preamps and crossovers that are degrading the signal in the first place?
     
  4. Chriss M

    Chriss M Well-Known Member

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    sure

    what is happening is that in direct mode, your cd player is getting the digital information from the and converting it to analog. It's sending the signal to your receiver or pre/pro which is simply passing it along to your amplifier and out to your speakers. This is the most direct path for the signal but because your pre/pro only has digital crossovers, it's not able to properly cross over the bass information to your sub.

    In stereo mode, the cd player is converting the signal to analog and sending it to the pre/pro, which is then converting it BACK to digital, doing the crossover work, and finally converting it yet again back to analog for output. Additional conversions cause a loss of quality, and the DAC in your pre/pro may not even be as good as the one in the CD player. So you're getting the bass output from the sub that you want but losing overall sound quality.

    An external analog crossover will let you keep both. You can use direct mode and the signal will not be converted by the pre/pro. it will output the original analog signal to your crossover which will be perform the crossover to the sub in the analog domain, without any additional conversions. So, you get the high quality output from your CD player's DAC's, and you get the bass output from your sub.

    hope that made some sense
     
  5. BruceD

    BruceD Well-Known Member

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    Rob,

    I have found similiar results and have resorted to an external xover like Chris indicated. Below is a description:




    Combo 2-Channel and HT System


    Amplifier:



    Parasound 1205A 5 Channel amp (200wpc @4 Ohms)


    Preamplifier (or None if Integrated):



    Parasound 1100-D Direct Stereo Pre-amp


    Marchand XM9L Deluxe 2way electronic xover


    with 24dB slope Linkwitz-Riley symmetrical crossover at 60Hz.


    -This is inserted between the L&R analog out of the Parasound 1100D pre-amp and the L&R main analog input of the Parasound 1205A amp.


    -The L&R low pass out from the xover is summed (with a sum switch) and sent to a BFD 1100P Parametric EQ.


    -Output from the BFD is sent to the subwoofer's analog mono input.


    Speakers:



    Main L&R are Dynaudio Contour 2.8 towers. These are 2-way systems with the Confidence series tweeter and a 6.5 inch passive radiator to go with the 6.5 inch mid-bass. These are rated at -3dB to 32Hz, so I tested the Marchand xover and found the best match with the sub at 60Hz, about an octave above 32Hz.


    Subwoofer is an M&K MX-700 powered sub.


    Sources:


    CD Player/DAC:



    Parasound 1500-C 5 Disc CD player


    Turntable/Phono Stage:



    Technics SL-D2 with Grado Blue


    Radio Shack phono preamp


    Other Accessories/Room/Misc.:


    Speaker Cables/Interconnects:



    Kimber Cable 4TC speaker cable for Mains and Radio Shack Gold for interconnects


    Tweaks:



    Marchand XM9-L electronic crossover (mains-sub)


    Behringer BFD 1100P Parametric EQ (sub only)


    Room Size (LxWxH):



    13 x 19 x 8-12 cathedral ceiling


    Music Preferences and Comments:


    Music Used (Genre/Selections):



    Jazz (FourPlay, David Benoit, Boney James), Female vocals, instrumentals


    System Goals/Comments:



    This integration of 2-channel music and HT is pretty good, but 2-channel soundstage does suffer some because of TV cabinet.


    System Strengths:



    Dynaudio main speakers present that vocal realism from female vocalists that really stirs my emotions. Also on many of my favorite jazz pieces my foot can't stop moving to the beat.


    System Weaknesses:



    At this time I am very happy with my setup, only soundstaging is a bit less than optimal.


    Video/HT System: Integrated


    TV/Projector:



    Toshiba TN36 36" Direct view 4x3


    Processor/Receiver/Amplifiers:



    Technics SH500D DD/DTS processor


    Main L&R analog out -- Aux L&R analog in on Parasound 1100D stereo pre-amp


    Center analog out -- Parasound 1205A amp


    L&R surr. analog out -- Parasound 1205A amp


    Subwoofer out -- nothing


    Subwoofer output turned off in software and re-routed to L&R mains


    Speakers (Center, Surrounds, Sub):



    Center is the Dynaudio Contour center.


    Surrounds are Dynaudio Contour 1.1 mini-monitors.


    Subwoofer is an M&K MX-700 powered sub.


    Sources (DVD/VCR):



    Toshiba 3108 DVD player with digital optical in to the Technics SH500D
     
  6. Chriss M

    Chriss M Well-Known Member

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    sure

    what is happening is that in direct mode, your cd player is getting the digital information from the and converting it to analog. It's sending the signal to your receiver or pre/pro which is simply passing it along to your amplifier and out to your speakers. This is the most direct path for the signal but because your pre/pro only has digital crossovers, it's not able to properly cross over the bass information to your sub.

    In stereo mode, the cd player is converting the signal to analog and sending it to the pre/pro, which is then converting it BACK to digital, doing the crossover work, and finally converting it yet again back to analog for output. Additional conversions cause a loss of quality, and the DAC in your pre/pro may not even be as good as the one in the CD player. So you're getting the bass output from the sub that you want but losing overall sound quality.

    An external analog crossover will let you keep both. You can use direct mode and the signal will not be converted by the pre/pro. it will output the original analog signal to your crossover which will be perform the crossover to the sub in the analog domain, without any additional conversions. So, you get the high quality output from your CD player's DAC's, and you get the bass output from your sub.

    hope that made some sense
     
  7. Charles J P

    Charles J P Well-Known Member

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    CJ Paul
    CWhat receiver are you using? By your use of terms direct and stereo it sounds like you are talking about Marantz. Also, be careful about genrealizing how different receivers handle processing. I am currently researching the possibility of purchasing a high end CD player but didnt want to "waste" the players DACs by redigitzing the signal, etc. So, I've been exchanging emails with Yamaha, and so far the news is that my RX-V1200 does bass management in the analog domain. There are just a few other issues that I am following up on, but as my adventure relates to Criss M's post, there are receivers (affordable ones even) that do bass management in the analog domain.
     
  8. RobWil

    RobWil Well-Known Member

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    Thanks very much for the responses. Yes Chriss, that makes perfect sense. I didn't realize there were additional conversions going on.
    To be more specific, I am using an Onkyo TX-SR797 with an HK HD7600II cd player. I think the DAC's in my cd player are definitely superior to the receiver's.
    Charles....I do not believe I have any options on bass management in the direct mode. I think mine works just as Chriss describes (unfortunately).
    The difference in the non-bass sound in direct vs stereo is quite profound, as is the difference in bass sounds in stereo vs direct. A limitation of my main speakers woofers no doubt. The sub is an Infinity IL120S.....not the best but certainly no slouch either.
    BTW...the Onkyo is new so I'm not intimately familiar with it. It could have some bass management feature I'm not aware of.
     
  9. Mike Up

    Mike Up Well-Known Member

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    Charles,

     
  10. Charles J P

    Charles J P Well-Known Member

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    CJ Paul
    They didnt skate around it with me.

    First response:
     
  11. RobWil

    RobWil Well-Known Member

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    Boy...did I have my head up my butt or what!? Well...with the help of the manual anyway....I guess you could say I 'manually' put my head up my butt? Nyuck, nyuck...

    Anyway, I DID mention this was a new receiver didn't I???
    The friggin' Re-EQ setting was on! That's why it sounded so much better in Direct mode because this setting is bypassed for Direct!
    In my defense there are actually 2 Re-EQ settings...one under 'THX Setup' and one under 'Audio Adjust>Sound Effect'. I had seen the explanation under 'THX Setup' and it says "This parameter is only enabled for the THX listening mode" so I figured it was ignored any other time.
    Now I see it under 'Audio Adjust>Sound Effect' and it says "This can be set to either 'On' or 'Off'. This parameter is enabled for listening modes OTHER THAN the THX, T-D, Direct, PL II Music, or Neo:6 Music listening mode". Why on earth would anyone want to use this for ANY music mode??? All it does is chop off your high end, fer crying out loud!
    Now I can't really tell much difference between stereo and direct modes....besides bass I mean....which is much better in stereo mode.
     
  12. RobWil

    RobWil Well-Known Member

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    So another question now.....
    Chriss says, quote "In stereo mode, the cd player is converting the signal to analog and sending it to the pre/pro, which is then converting it BACK to digital, doing the crossover work, and finally converting it yet again back to analog for output. Additional conversions cause a loss of quality, and the DAC in your pre/pro may not even be as good as the one in the CD player. So you're getting the bass output from the sub that you want but losing overall sound quality."

    So, DAC's being equal, would you technically be better off using the digital out from the cd player so that the receiver just has to worry about the one conversion to analog?? I'm assuming the receiver takes the digital signal, does it's crossover work, then does the analog conversion? Actually I've done some switching back and forth and found this:
    1. Whether I use analog or digital out to receiver, in direct mode both sound about equal, but of course I lose my sub.
    2. In stereo mode, the analog out to receiver sounds better than the digital out. However, with the digital out, if I then turn on the 'upsampling' feature on the receiver, which doubles the sampling frequency, they sound about equal. This would tend to indicate that the DAC's on the CD player are better than on the receiver, but then the upsampling might be enough to equal them out some? But it doesn't explain why in direct mode the analog and digital out sound about equal. You would think the analog out would sound better if indeed the CD players DAC's were better.
     

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